

		\centering
		\begin{tikzpicture}
			
			% 同一个父亲的孩子锚定点间的距离 层间距离
			\begin{scope}[sibling distance=8pt, level distance=27pt,scale=2] 
				\Tree[.\node(a1){$=$};
				[.\node(b1){$*$};]
				[.\node(b2){$+$};
				[.\node(c1){$*$};
				[.\node(d1){a};]
				[.\node(d2){b};]
				]
				[.\node(c2){c};]
				]
				]
			\end{scope}
			
		\end{tikzpicture}
	
